By Sponsor it would probably mean they pay their dues to the MC, every month. The instructor is probably a member or an associate with close ties. Personally, I would avoid the club only because I have friends in other clubs and wouldn't want to cause any friction with my friends. It's difficult enough that my friends are in different clubs, adding to the mix that I would be training in a club that's entirely different from theirs, ****, I'd want to be learning how to defend myself real good.

It could also be a breeding ground, they'd see who has a knack for intimidation, who gets on well with the club. It could also be a front business, especially if they have "cash deals" for members.

Agreed. A family member of mine is a prez at a MC chapter here in OR. You are most likely dead on. Gym owner is probably patched. Most MC guys have families and kids like everyone else. They just have a different way of living life. Good guys to be friends with, not so good to be enemies with.

As for the original question, it would depend on the circumstances. It seems from you wrote that it wouldn't be the best fit for you. Although, I bet they train hard.